How to combine these mysql queries

Query 1

$query = "SELECT stock_issue.*,stock_item.item_name
FROM stock_issue,stock_item
WHERE stock_issue.idate>=$from
AND stock_issue.idate<=$to
AND stock_issue.item_id=stock_item.ID
ORDER BY stock_issue.idate DESC";

Query 2

$query = "SELECT stock_purchase.*,stock_item.item_name
FROM stock_purchase,stock_item
WHERE stock_purchase.pdate>=$from
AND stock_purchase.pdate<=$to
AND stock_purchase.itemid=stock_item.ID
ORDER BY stock_purchase.pdate DESC";

SELECT stock_issue.*,stock_item.item_name
FROM stock_issue,stock_item
WHERE stock_issue.idate>='$from'
AND stock_issue.idate<='$to'
AND stock_issue.item_id=stock_item.ID
ORDER BY stock_issue.idate DESC
UNION
SELECT stock_purchase.*,stock_item.item_name
FROM stock_purchase,stock_item
WHERE stock_purchase.pdate>='$from'
AND stock_purchase.pdate<='$to'
AND stock_purchase.itemid=stock_item.ID
ORDER BY stock_purchase.pdate DESC